This invention relates to 1-alkyl-6,8-difluoro-7-heterocyclic-1,4-dihydroquinol-4-one 3-carboxylic acids and their esters and cation salts, and the acid addition salts thereof, the preparation of said compounds, antibacterial compositions containing said compounds and a method of using said compounds.
Since the introduction of nalidixic acid in 1963, a considerable number of patents and scientific papers have been published on analogs of this compound. Representative of these publications are U.S. Pat. No. 3,753,993 describing compounds of the formula ##STR1## in which PY is 3- or 4-pyridyl, R may be hydrogen and R.sub.1 may be short chain alkyl, and U.S. Pat. No. 3,907,808 disclosing compounds of the formula ##STR2## wherein R may be hydrogen, R.sup.1 a short chain alkyl and PY is 2-,3- or 4-pyridyl which may be further substituted. R' of U.S. Pat. No. 3,907,808 is a substituent in the 5 or 6 position which may be halo. Compound 57A of the patent has a fluoro at the 6 position. Neither patent discloses 6,8-difluoro substitution.